Afterglow -triple quadrupole

Alternatively, the translational energy threshold for endothermic proton transfer from MH+ to R can be measured using a flowing afterglow triple quadrupole instrument.127 These data define the proton affinity of M, relative to that of R. Thus, the PA of cyclopropenylidene was found to exceed that of ammonia by 23.3 1.8 kcal/mol (Table 6).128 In order to obtain absolute proton affinities, the enthalpies of formation of both the base and the conjugate acid must be known from other measurements (Eq. 9). Numerous reference compounds with known absolute PA are available.124... 

Abstraction of H2+ from 3-methylanisole, generated in a flowing afterglow triple quadrupole apparatus, gives the radical anion (18). This species undergoes electron transfer to F2 followed by attack of fluoride ion at the methoxy methyl group to give the distonic carbene ion Carbene (19) displays reactivity characteristic... 

More recently, a new set of data was obtained by measuring with a flowing afterglow-triple quadrupole apparatus the threshold energy for the reaction of equation 45 (X = F, Cl) under CID conditions324. 

The hydride affinity of BH3, measured in a tandem flowing afterglow-triple-quadrupole apparatus, is 74.2 2.8 kcal/mol [13]. As mentioned above, experimental measurements on the appearance potentials for [BH]", [BH2Y, and [BH3]" from BH3 were obtained using photoionization mass spectrometry. The values are <13.372 0.015 eV, <12.819 0.02 eV, and 12.026 0.024 eV, respectively. The study gives AfHo values ranging from 22.2 3.4 kcal/mol to 25.8 1.7 kcal/mol, depending on the value used for the heat of atomization of boron [6]. 

The flowing afterglow-triple quadrupole technique has been used to measure the diastereoselectivity of the reduction of a range of cyclohexanones by silicon hydride ions in the gas phase. Strikingly, the axial or equatorial preferences in these intrinsic diastereoselectivities are consistently similar to results in condensed phase. 

The energetics and mechanism of the decarboxylation of the hydroxycarbonyl compound [Fe(C02H)(C0)4], and its reactivity toward SO2 has been investigated using the flowing afterglow-triple quadrupole technique. The... 

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